The present invention relates to a method and an apparatus for manufacturing a filter from an endless web of filter material.
A method of this kind is disclosed in European Patent 260,267 and an apparatus of this kind is disclosed in German Patent 25 23 424, for the manufacture of air filter inserts, for example.
A disadvantage of manufacturing filter inserts by the method described in European Patent 260,267 is that, after the pleating of the filter material, the filter material is loose as it enters the screw, which is a comb-like part intended to define the projections. This loose transfer can result in damage to the filter material and cause leaks in it.
It is possible, as described in German Patent 25 23 424, to convey the pleated filter material into the screw by means of a complicated drive mechanism. This is, however, very expensive, and would increase the cost of the method and with it the cost of the end product. It furthermore calls for a greater cost of assembly and complicated adjustment in operation.